Embodiments of the inventive concepts relate to three-dimensional (3D) semiconductor devices and, more particularly, to highly integrated 3D semiconductor memory devices.
Semiconductor devices may be highly integrated to provide excellent performance and low manufacture costs. The integration density of semiconductor devices may directly affect costs of the semiconductor devices, and may thereby result in a demand of highly integrated semiconductor devices. The integration density of a conventional two-dimensional (2D) or planar semiconductor devices may be mainly determined by an area where a unit memory cell occupies. Therefore, the integration density of the conventional 2D semiconductor devices may be affected by a technique of forming fine patterns. However, since extremely high-priced apparatuses may be needed to form fine patterns, the integration density of 2D semiconductor devices may continue to increase but may still be limited. Thus, three-dimensional (3D) semiconductor memory devices have been developed to improve over the above limitations. 3D semiconductor memory devices may include memory cells three-dimensionally arranged.